For many vehicles having toilet systems, particularly marine vessels, it is desirable to provide effective and relatively large holding capacity for the sewage, which may be ultimately legally discharged. Such tanks, however, typically have nauseating odors associated therewith, have breakdowns in equipment, and in general can be a nuisance that can render a very expensive craft unpleasant to operate. According to the present invention, a system, and individual component parts thereof, are provided which allow effective odor control of the holding tank over significant periods of time, to allow practical on-board retention until discharge is legally permissible, without odor problems.
According to the present invention, a holding tank is provided with a gas vent in the top thereof through which odoriferous gases pass, such as--in particular--hydrogen sulfide and amino acid odors. An in-line filter, comprising a tubular housing with end terminations and retaining means adjacent each end for retaining activated carbon within the housing, is provided. The filter does not offer significant resistance to air flowing therethrough, and contains two different types of activated carbon, a first (about 90%) particularly effective against hydrogen sulfide, and a second particularly effective against amino acid gaseous compounds.
Additionally, odor control chemical is injected into the tank. It has been found, according to the present invention, that maximum odor control with a minimum amount of chemical usage is provided when a small and predetermined amount of chemical is injected into the tank on a periodic basis. The chemical is injected after a significant amount of bacteria build-up but before exponential growth of the bacteria. A chemical injection pump remote from the tank provides for the injection.
In order to facilitate odor control and tank discharge operations, a tank cap is provided in the top of the tank, the cap in removable sealing relationship with the tank top. The odor vent and chemical injection take place through the tank cap, and additionally the tank cap has operatively mounted thereon a pair of level indicator switches, such as "Reed" switches, one indicating a "high" level of liquid in the tank, and the other indicating that the tank is "full." The tank cap also can be provided for other purposes, such as allowing the passage of tank cleaning apparatus therethrough. The level switches are operatively connected to a control panel, which also controls the chemical injection, and controls the discharge pump.
A discharge pump is operatively connected adjacent the bottom of the tank, at a point where a downwardly sloping bottom wall of the tank is at its nadir. A downwardly disposed flexible conduit loop connects the bottom portion of the tank to the discharge pump and an upwardly extending conduit loop connects the discharge pump to a nozzle discharge system which is below the waterline of a marine vessel. The top of the upwardly extending loop is at least a foot above the waterline of the vessel.
The tank, hoses and other components are selected so that they do not pass odors. Such components, such as hoses that will not pass odors, may be purchased from SeaLand Technology, Inc., of Big Prairie, Ohio.
A tank cleaning device which may be utilized according to the invention comprises a piece of flexible tubing, such as surgical tubing, connected at a first end thereof, to or adjacent a wall (preferably the top wall) of the tank and in communication with a source of fluid (preferably liquid) under high pressure. The free end of the tubing has a nozzle associated therewith, the nozzle having significant mass and also significantly restricting the flow of fluid therethrough and thereby increasing its velocity. The tube has sufficient length so that when fluid under pressure is supplied to the interior thereof, the tube will thrash wildly within the tank, and dispense fluid in the tank while the nozzle impacts against the tank walls.
It is a primary object of the present invention to provide a vehicle toilet system holding tank assembly or the like that has excellent odor control. This and other objects of the invention will become clear from an inspection of the detailed detailed description of the invention, and from the appended claims.